Sand drying apparatus



NOV- 13, 1951 A. M. cowEsURN SAND DRYING APPARATUS 2 SHEETS--SHEET l Filed March 19, 1948 @www Nov. 13, 1951 A, M. COWBURN 2,574,911

SAND DRYING LAPPARATUS Filed March 19, 1948' 2 'SHEETS- SHEET 2 atentec lNov. 13, ,1,951

OFFICE y 2,574,911 SAND DRYING APPARATUS Allan MauriceCowburn, Islington, New South Wales, Australia Application March 19, 1948, Serial No. 15,887 In Australia March 24,1947

f claims. (orar- 171) This invention relates to apparatus `for use in drying sand for 'use in the' manufacture of glass, in forming cores for use in foundries, in lcoppersrhithing and such other industries inwhich'moisture in the `sand is harmful 'or undesirable. Itis applicable to thevertical type ofvsand dryingapparatus in which the 'sand in its'moist state is fed in at the top and gravitates past heated elements in 'its course to the point of discharge.

In apparatus of this type already in use, a container Vis provided, having Va central 'cone with na flue `at its apex, the sand being on the upper suriace of the cone, which is heated from below. An outercasing of gauze or perforated metal allows the dried sand to escape.

This arrangement allows the sand'to form a crust and to consolidate into a Ymass through which the 'steam generated bythe contact ofthe damp sand with the'heated cone,must pass. 'This causes a'retardation 'of the drying ofthe Abalanc of the sand.

The escape of `the Vheated air and/or Vgases through the flue before the 4maximum 'heat has been lextracted from vthem combined Vwith the slowness of drying makes this process both inei ii'cient in output and costly `of operation. l

It is the object of this invention to overcome these defects by providing van apparatus in which the sand is caused to Apass successively overheated cones which rst narrow Aand then enlargeso that the sand is not permitted to form a crust or -consolidate in regular masses. Steam is thus readily liberated and 'escapes 'without appreciably retarding the drying of the balance lofthe sand.

The heated air and/or gases are'not conveyed directly away by the ue but by means of escape vents or orifices from the major heating cone are directed to other parts 4of the drier where they combine withv the steam from'the sand Vin heating other conesurfaces until as much heat 'as .possible has been extracted consistent with the desired speed of drying being maintained and the 'steam being released at a temperature high enough to prevent its lcondensation in `undesirable quantities. It will be appreciated that whereas with moist sand a greater -degree of heat may be extracted lwith less steam formation,"where vwet sand is being treated a very considerable'degree of 'steam formation and condensation is likely. This may lbe minimised vby providing 'special means such as drainage trays to deal lwith the condensate. In a modification the steam and fumes may be exhaustedby mechanical means,

but in this instance the degree of heat-extraction by a baille varrangement against and along the surfaces they are designed to heat. Where the sand dryer is located adjacent to a source of heat,l such as an annealing furnace, core stove or the like, a flue pipe carrying waste vflue gases Vmay 'be introduced under the main cone as in the form described for coke burning. Adjustable means are provided for the escape of the dried sand'and for separation of foreign matter.

When treating sand which has not a great deal of moisture content with the cones heated by oil, gas or electricity, it is `found that particles of sand in direct contacteither with the interior cone formations or with thevents irom'which the heated `gases issue, become dried before they approach the point of discharge. In such circumstances I provide a number of perforationsin the cones and/or vents and lallow the dried sand to fall direct to the -collecting means. This permits other particles to have direct contact with the heated cones and vents and accelerates the speed of operation.

In order to describe the invention more fully, reference will now be made to the drawings accompanying and forming part of this complete speciiication and where:

Fig. 1 is a partly sectional elevation of a sand dryer suited for heating by a gas burner.

Fig. 2 is a vertical section of the unit taken on the line 2--2 of Fig. 3.

Fig. 3 isan venlarged horizontal section on the line 3-.3 of Fig. 2.

Fig. 4 shows an elevation of the sand dryer adapted for heating from a coke `or oil burning unit, or waste flue gases.

Fig. V5 shows a suitable baiile arrangement for converting from a direct heating unit to a unit suitable for indirect heating .as by waste flue gas., coke,oil or the like.

The sand drier consists of an open ended cylindrical container or casing 3, supported upon legs 4, having their upper ends inset and welded to plates 5, alixed to the container side wall .by screws or the like. The lower ends of the legs 4, have feet 6, thereon and are connected by ang-ular braces 1, and horizontal bar 8.

A vscreen 9, is Iitted across the mouth oi the container 3, above a hopper In. The hopper Ill, is of metal of inverted frusto-conical form, open at both ends, the lower or smaller end having positioned within it cone II, which is attached to the top of a. hollow frusto-conical primary sanddrierV I2 axially aligned with the hopper IG.

The cone or primary sand drier I2 is retained in position by the cone supports I3 or equivalent supporting means. VThe supports I3 as shown are vertical sheets of metal aixed to the inner wall of casing 'I3 and the upper surface of cone I2. Escape vents I, having welded to them a circular baiile plate I'5 which may be described as a sand ow retarding barile ring, project from cone I2. The lower edge of baille ring I is spaced from the surface of cone I5. A regulating band or annular Shutter I6 is controlled by screw threaded studs II upstanding from the bottom of cone I2 and thereby fixed in relation to the container 3. The studs pass through orices I8 in the lugs I9 that extend outwardlyV from the band I6. The band or shutter I6 may be man- Y Heat is supplied in this form of the invention by gas burners 20 which in a lpreferred formare circularly arranged. The burners are supported by burner supports 2Iv attached to an inverted hollow frusto-conical secondary sand drier 22 which in turn is placed in fixed relation with the container 3 by supports 23 attached to legs 4. The secondary sand drier 22 being exposed to the open flame of burners 20 is also heated thereby. Sieve 24 is Supported in frame 25.

In the coke fired model as illustrated in Fig, 4, the gas burners 20 and supports 2| are removed and in their place is inserted the baille arrangement illustrated in Fig. 5.

The coke burner 21 is connected by ue 28 to the space 29 which is surmounted by the circular baille 30 carried on supports 3 I.

Steam and fume escape holes 32 are in this form of the invention covered by flues 33.

y In the form illustrated in Fig. 1, perforations, not shown, may be made in the cone I2 and/or the hollow projecting vents I4.

In operation, the sand to be dried enters the hopper I 0 through the screen 9 which removes coarse foreign matter. Its flow is restricted and confined through the annular space 35 between hopper I0 and the conical apex I I. It then passes over the upper surface of primary drier I2, the thickness of the sand diminishing as the circumference of the cone increases, so that if the sand coming through the annular space 35 is two inches in thickness, it has diminished to about 11A inches by the time it has passed under the baille ring I5 and to about 1%; inch as it slides down the balance of the outer surface of the cone I2, past the annular baille band 40, to the space 36 inside the annular discharge regulating band or shutter whence it falls through the controlled space between the shutter IB and the primary drier I2 into the inverted lower secondary drier 22 and so through the sieve 24 where finer particles of foreign matter are removed.

Heat is applied in Fig. 1 by means of a circular gas burner 20 which heats the underside of the primary drier I2 and its apex II as well as the secondary drier 22. The hot air and fumes escape from primary drier I2 by the hollow projection vents I4 but are trapped in the space 31 where they mingle with the steam from the sand and assist to heat the underside of the hopper I0. When the requisite degree of heat has been extracted from the gases, they are allowed to escape by the escape holes 32. Smaller escape holes 39 are provided at a higher location to permit the escape of steam before it has condensed.

Steam escape holes 4I are also provided below baille 40 to prevent condensation of steam generated in the lower portion of the container 3, while holes 42 permit escape of steam and sand.

In the form illustrated in Fig. 4 steam escape holes 39 are eliminated, as the steam and fumes are withdrawn by duct or mechanical means.

The discharge regulating band I6 may be manually raised to release foreign matter from the interior of the drier.

Although in this specification the invention has been described as for the pur-pose of drying sand, it is also applicable to certain types of granulated materials such as metal chippings, filings, stone dust and the like.

I claim:

1. Gravity-fed sand-drying apparatus comprising an inverted frusto-conical feed hopper open at both ends, a hollow conical primary sand-drier mounted axially beneath said hopper and having the apex projecting through the open base of the hopper to form an annular feed opening for gravitational flow of sand from the hopper onto the external conical drying surface of said primary drier,r annular baliies outstanding from the external surface of said primary drier and posi-v tioned in spaced relation between the annular feed opening and the base of said primary drier for impeding the gravitational flow of sand upon the external drying surface of said primary drier, an inverted hollow frusto-conical secondary sand-drier mounted axially beneath the primary sand-drier so as to receive sand from said lpri` mary drier, shutter means at the base of the primary drier for regulating gravitationa1 transfer of the sand from the primary drier to the secondary drier, a sand discharge opening at the lower end of said secondary drier, and means for heating the drying surfaces of said primary and secondary driers.

2. Gravity-fed sand-drying apparatus comprisf ing an inverted frusto-conical feed hopper open at both ends, a hollow conical primary sanddrier mounted axially beneath said hopper and having the apex projecting through the lower open end of the hopper to form an annular feed opening for gravitational flow of sand from the hopper onto the external conical drying surface of the primary drier, a sand-flow retarding baffle ring fixed with respect to and vertically upstanding and spaced from the external conical surface of the primary drier to form a restricted clearance therebetween and positioned in the vicinity of said annular feed opening and between said annular feed opening and the base of the primary drier. a sand-flow retarding annular bafe band arranged angularly from the external conical surface of the primary drier to form a restricted clearance between said external conical surface and the adjacent edge of the baille band and located between said baille ring and the base of the primary drier, an inverted hollow frusto conical secondary sand-drier mounted axiially beneath and adjacent the hollow conical primary drier said secondary drier having an axial discharge opening and the inverted base diameter exceeding the base diameter of the primary drier, a vertically-adjustable annular shutter upstanding from and surrounding the .base of the hollow conical primary drier for regulating gravitational transfer of the sand from the base of the primary conical drier to the secondary drier, and means for heating the primary and secondary driers.

3. Gravity-fed sand-drying apparatus comprising an inverted frusto-conical feed hopper open at the lower end and having a screening sieve at the upper end thereof, a hollow conical primary sand-drier mounted axially beneath said hopper and having the apex projecting through the lower open end of the hopper to form an anl nular feed opening for gravitational flow of sand from the hopper onto the external conical drying surface of the primary drier, a sand-flow retarding baille ring fixed with respect to and vertically upstanding and spaced from the external conical surface of the primary drier to form a restricted clearance therebetween and positioned in the vicinity of said annular feed opening and between said annular feed opening and the base of the primary drier, a sand-flow retarding annular bafe band arranged angularly from the external conical surface of the primary drier to form a restricted clearance between said external conical surface and the adjacent edge of the baiile band and located between said baille ring and the base of the primary drier, an inverted hollow frustoconical secondary sand-drier mounted axially beneath and adjacent the hollow conical primary drier said secondary drier having an axial discharge opening and the inverted base diameter exceeding the base diameter of the primary drier, a vertically-adjustable annular shutter upstanding from and surrounding the base of the hollow conical primary drier for regulating gravitational transfer of the sand from the base of the primaryconical drier to the secondary drier, a screening sieve at the discharge opening of the secondary k.

drier, and heating means positioned in the space between the hollow conical primary drier and the inverted hollow frusto-conical secondary drier for heating said driers.

4. Gravity-fed sand-drying apparatus comprising an inverted frusto-conical feed hopper open at the lower end and having a screening sieve at the upper end thereof, a hollow-conical primary sand-drier mounted axially beneath said hopper and having the apex projecting through the lower open end of the hopper to form an annular feed opening for gravitational ow of sand from the hopper onto the external conical drying surface of the primary drier, a sand-flow retarding baille ring fixed with respect to and vertically upstanding and spaced from the external conical surface of the primary drier to form a restricted clearance therebetween and positioned in the vicinity of said annular feed opening and between said annular feed opening and the base of the primary drier, a sand-flow retarding annular baffle band arranged angularly from the external conical surface of the primary. drier to form a restricted clearance between said external conical surface and the adjacent edge of the baffle band and located between said baille ring and the base of the primary drier, a casing forming a hot-gas chamber around the hopper and the primary drier and vented at the upper portion for escape of spent gas, an inverted hollow frusto-conical secondary sand-drier mounted axially beneath and adjacent the hollow conical primary drier said secondary drier having an axial discharge opening and the inverted base diameter exceeding the base diameter of the primary drier, a vertically-adjustable annular shutter upstanding from and surrounding the base of the said hollow conical primary drier for regulating gravitational transfer of the sand from the base of the primary conical drier to the seci. ondary drier, a screening sieve at the discharge opening of the secondary drier, means positioned in the space between the hollow conical primary drier and the inverted hollow frusto-conical secondary drier for heating said driers, and means for directing the hot gases from the hollow conical interior of said primary drier into said hotgas chamber and in the vicinity of said hopper.

5. Gravity-fed sand-drying apparatus comprising an inverted frusto-conical feed hopper ....open at the lower end and having a screening sieve at the upper end thereof, a hollow conical primary sand-drier mounted axially beneath said hopper and having the apex projecting through the lower open end of the hopper to form an annular feed opening for gravitational flow of sand from the hopper onto the external conical drying surface of the primary drier, a sand-flow retarding baie ring fixed with respect to and vertically upstanding and spaced from the external conical surface of the primary drier to form a restricted clearance therebetween and positioned in the vicinity of said annular feed opening and between said annular feed opening and the base of the primary drier, a sand-flow retarding annular bailie band arranged angularly from the external conical surface of the primary drier to form a restricted clearance between said external conical surface and the adjacent edge of the baille band and located between said baiile ring and the base of the primary drier, an inverted hollow frusto-conical secondary sand-drier mounted axially beneath and adjacent the hollow conical primary drier said secondary drier having an axial discharge opening and the inverted base diameter exceeding the base diameter of the primary drier, a vertically-adjustable annular shutter upstanding from and surrounding the base of said hollow conical primary drier for regulating gravitational transfer of the sand from the base of the primary conical drier to the secondary drier, a casing forming an annular hot-gas chamber around the hopper and the primary drier by surrounding said hopper and primary drier from the top of the hopper to adjacent the top of the vertically-adjustable shutter and vented at the upper portion for escape of spent gas, a screening sieve at the discharge opening of the secondary drier, means positioned in the space between the hollow conical primary drier and the inverted hollow frusto-conical secondary drier for releasing hot gases therein to heat said driers, and a plurality of hot-gas fiues passing through the wall of said hollow conical primary drier and extending from the hollow conical interior thereof into said hot gas chamber and in the vicinity of the under surface of said hopper for directing hot-gases against said hopper.

ALLAN MAURICE COWBURN.

REFERENCES CITED The following references are of record in the y ille of this patent:

UNITED STATES PATENTS 

